Hello,my laptop has one jack 3.5 output connector, sometimes i am using headphones and sometimes laptop internal speakers. I am afraid of the wear of the jack connector connection to the motherboard and also it is bothering to always manualy plug the connector. Is there any way to keep headphones connector plugged and do the simple switching (internal speakers/headphones)? (this is M$ Windows).

can't.You should destroy the current plug assembly inside and wire again.Because headphone jack triggers the physical switch inside the jack hole, and then the switch turns off the internal speaker while accepting signal from the headphone wire.